This invention relates to new and useful improvements in the production of resin binders and accelerators, to the process for applying these materials to discrete, inert solid particles, and to the compositions produced thereby.
Resin binder compositions that have proven commercially successful, especially because of the high cure speeds obtainable when using these compositions, are binder compositions which comprise a liquid one-step phenol formaldehyde resin component such as urea formaldehyde. Such resin binder compositions and the method for using them are disclosed in U.S. Pat. No. 3,306,864, and a particular class of such resin binder compositions is disclosed in detail in U.S. Pat. Nos. 3,539,484 and 3,852,232. Such resin binder compositions have become widely accepted in the foundry industry and are especially desired because of their high cure speeds. However, increasing refinements in this technology are making new demands upon the characteristics of these materials. More intricate patterns for foundry cores require materials having greater ability for the wet mixture of foundry sand, accelerator and resin composition to flow into detailed pattern designs. Industry is also demanding greater moisture resistance of the cured foundry molds and cores.
Accordingly, it is an object of this invention to provide improved resin binders and accelerators which are capable of improving the flow characteristics of wet mixtures of sand containing them. It is a further object of the invention to provide improved resin binders and accelerators and systems which when cured with foundry sand provide molds and cores with improved moisture resistance. These and other objects of the invention will become apparent from a consideration of the following detailed disclosure.